The present invention relates generally to fluid control devices, and more particularly to a directable free jetstream type valve.
Fluidic valves are well known for providing control functions for moving fluid streams. One type of fluidic valve currently in use is disclosed in U.S. Pat. No. 3,612,103 in the name of M. B. Waddington and issued July 1, 1969. This device is a deflector jet servovalve which has an electromagnetic torque motor and two stages of hydraulic power amplification. Two permanent magnets are arranged in parallel between the upper and lower polepieces of the torque motor. The motor armature extends into the two air gaps located between these polepieces. A flexure tube supports the armature for rocking motion caused by magnetic forces developed at the air gaps. The flexure tube also seals the torque motor cavity from hydraulic fluid. The first stage of the deflector jet servovalve is a disc defining a fluidic amplifier containing a fixed pressure jet and two receivers. The fluidic disc is contained between cylindrical end covers which provide the top and bottom walls for the fluid amplifier. A jet stream deflector is located in the return pressure chamber between the pressure and receiver openings. The deflector contains a V-shaped slot that straddles the jet. At the upper end the deflector member attaches rigidly to the mid- point of the armature so that armature motion moves the jet deflector from side to side. The differential flow or pressure developed between the receivers is applied to the ends of a second-stage spool.
The design of the first-stage of the servovalve is complex and it is not capable of high frequency response and passive recovery.